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Entry  Wed Dec 21 04:29:01 2011, kiwamu, Update, Green Locking, Power Recycled Single Arm time_series.png
    Reply  Wed Dec 21 16:55:30 2011, kiwamu, Update, Green Locking, Power Recycled Single Arm 
Message ID: 6144     Entry time: Wed Dec 21 16:55:30 2011     In reply to: 6141
Author: kiwamu 
Type: Update 
Category: Green Locking 
Subject: Power Recycled Single Arm 
 I did some brief parameter checks for the power-recycled single arm which I have done yesterday.
The purpose is to make sure that the interferometer and I weren't crazy.
So far the measured quantities look reasonable.
  

         Assumptions on the parameter estimations          

   No losses.
   Tprm = 0.05637
   Titm =0.01384
   Tetm = 15 ppm
   Tbs = 0.5
 
        Parameter estimations and comparison with measurement      
   Recycling gain G = Tprm / (1 - ritm * rprm * Tbs) = 0.21 
   Amplitude reflectivity of the arm rarm =   (retm - ritm) / (1 - ritm * retm) = 0.99785
   Effective ITM's amplitude reflectivity ritm' = ( ritm + rprm * Tbs) / (1 + ritm * rprm * Tbs) = 0.9976
   Arm finesse = pi * sqrt (ritm' * retm) / (1 - ritm' * retm) = 1298
 
  + Power build up from single arm to power-recycled arm = G / Tprm = 3.73
      => measured value is 3.8 at maximum
 
  + Reflectance of the coupled cavity R = ( rprm -  rarm * Tbs )2 / (1 - rprm * rarm * Tbs  )2 =  0.841
     => measured value was about 0.85 at minimum
 
 
  + Cavity full linewidth = lambda / arm_finesse / 2 = 0.41 nm
     => narrower than that of the usual single arm by factor of 2.9
     => I guess this was the reason why the intracavity power looked more fluctuating after everything was locked

Quote from #6141

I made the first trial of locking a Power-recycled single arm.

 

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